The present disclosure relates generally to apparatus and methods for surgically proximating tissue, such as in closing a patent foramen ovale or other tissue defect.
The need to surgically proximate and attach segments of tissue arises under a plethora of different circumstances. Tissue defects, such as wounds, are one such example. Treatment of a skin surface wound typically entails suturing edges of the wound together. In many instances, however, the tissue defect to be treated is internally located, and thus not readily accessible by a surgeon otherwise attempting to utilize a conventional suture thread to effectuate repair of the defect. Access to internal tissue defects of these types through invasive surgery introduces a high level of risk that can result in serious complications for the patient, especially where the tissue defect is located at or near a vital organ. One example of an internal tissue defect of this type is a patent foramen ovale (“PFO”) that can occur between the left and right atria of the heart.
By way of reference, during development of a fetus in utero, most of the fetus' circulation is shunted away from the lungs through vessels or foramens that are open during fetal life. Normally, these specialized vessels and foramens will close shortly after birth. One such opening is known as the foramen ovale that allows blood to pass directly from the right atrium to the left atrium, thus bypassing the lungs. Following birth, and with establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in the functional closure of the foramen ovale, followed by formation of an anatomical seal with continued development of the heart.
In some instances, the foramen ovale fails to entirely close. This condition, known as PFO, may allow blood to continue to shunt between the left and right atria, posing potentially serious health risks. Other septal tissue defects can also occur and require treatment.
Invasive surgical procedures can be performed to address the septal tissue defects described above, as well as multiple other internal tissue defects. Alternatively, less invasive procedures, such as catheter-based procedures, have been suggested. In the context of PFO treatment, for example, expandable umbrella- or disk-like devices are delivered, via catheter, into the heart. Generally, the device is inserted through the natural opening of the defect, and the expandable structures are deployed to secure or bring together tissue segments surrounding the defect.
Alternatively, other internal tissue defect repair and/or tissue proximation techniques have been suggested in which a clip formed from a super elastic material is provided. The clip is self-transitionable from a deflected state in which the clip (or segments thereof) is at least somewhat linear, to an undeflected state in which the clip has a coiled curvature, thereby drawing opposing ends of the clip more closely to one another. During use, the clip is deployed, in the deflected state, to the defect site via a catheter or other minimally invasive apparatus. Upon deployment from the delivery tool, the clip reverts to the undeflected state or shape, with opposing ends or tips of the clip piercing through the tissue segments, pulling or proximating the segments into contact with one another. For example U.S. Pat. No. 6,776,784 describes that, in repairing a PFO, the clip ends are pierced through septum wall segments. The clip is then allowed to self-transition toward its natural or undeflected state (W-shape). This action, in turn, draws the tissue segments toward one another, serving to at least partially close the PFO. While viable, suggested clip configurations, and related applications, may not provide consistent, long-term closure of the defect. Similar concerns may also arise in the context of other tissue proximation or plication procedures, such as anastomosis, etc.
In light of the above, a need exists for improved devices, systems, and methods for surgically proximating tissue, for example closing tissue defects such as a PFO or other internal tissue defect.